Musical instrument



June 27, 1944. J. o. HRUBY, JR 2,352,438

MUSICAL INSTRUMENT Fgled Feb. 9, 1942 2 Sheets-Sheet 1 1 N VENTOR.

John O. Hrub ,Jn

HTTORNEY.

June 27, 1944. J o HRUBY, JR 2,352,438

MUSICAL INSTRUMENT I Filed Feb. 9, 1942 2 Sheets-Sheet 2 INVENTOR.

. rub J 1 11 aims? H T TORNE y- Patented June 27, 1944 UNITED STATES PATENT OFFICE MUSICAL INSTRUMENT John 0. Hruby, Jr., Glendale, Calif., assigncr to Louis A. Maas, Glendale, Calif.

Application February 9, 1942, Serial No. 439,987

1 Claims.

My invention relates to musical instruments, and more particularly to a musical instrument comprising a series of rods and a series of percussion means therefor, in combination with electronic pick-up devices and amplifying means.

An important object of the invention is to provide rods that may be tuned for fundamental and overtones or harmonic tones individually in a very accurate manner.

Another object of my invention is to provide such rods in which the fundamental can be changed.

My invention also has for its objects to provide a musical instrument that is positive in operation, convenient in use, economical of manufacture, relatively simple and yet producing fine musical tones.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description. However, the drawings merely show and the following description merely describes one embodiment of the present invention, which is given by way of illustration or example only.

In the drawings, like reference characters designate similar parts in the several views.

Figure l is a broken elevation of an embodiment of my invention looking in the direction of the arrows !l of Figure 3.

Figure 2 is a section taken along the line 2-2 of Figure 1 looking in the direction of the arrows.

Figure 3 is a plan View of an end portion of such embodiment.

Figure 4 is a section taken along line 4-4 of Figure 2.

Figure 5 is an enlarged elevation partly in section of a portion of a damping device comprised in this embodiment.

,Figure 6 is an enlarged section taken along the line 66 of Figure 2.

Figure '7 is an enlarged section taken along the line 'll of Figure 2.

, Figures 8 and 9 are sectional views of details which will hereinafter be more fully described.

Figure 10 is a broken elevation of a modified actuating means for the damping device.

Figure 11 is a digrammatic sketch showing part of the electric circuit of the embodiment.

Figure 12 is a modified actuating means.

Figure 13 is a further diagram of wiring employed in the embodiment.

Figure 14 is a perspective view of a modified construction of a rod.

reference number l5 generally designates framework upon which and within which is mounted my present musical instrument. The frame I5 includes a base [6, top bars IT and a cross support it, mounted on cleats l9 within the frame. Supported on the under side of the bars H is a series of rods 28, supported at their nodal points. One end of each rod 20 has a string or cord 21 passing through a transverse opening 22 substantially at one of the nodal points of the rod it]. The string 2| is in turn tied to brackets 33 on the under side of the bars ll, as best shown in Figure 6. The rods 29 are supported at the nodal points at the opposite end, by resting the bar Zliupon a non-metallic spool 24, which is supported on a bracket 25 by means of a string or cord 28, passed through a longitudinal passage in the spool 24, as best shown in Figure '7. The strings or cords provide flexible, non-rigid supports for the rods. The word string in the hereunto appended claims is to be interpreted to include the word cord.

' The rods 253 are of unique structure. They are cylindrical from. end to end and have been turned to produce a reduced diameter 21 at the central portion thereof. The reduced portion Z'l produces an overtone or harmonic tone when the rod is struck a percussion blow.

' To produce a fundemental tone, the rod has a circumferential groove 28 substantially in the longitudinal center of the rod. The groove 28 may likewise be placed in the rod by turning. It will be noticed that the reduced portion 21 and groove 28 are simply means for providing harmonic or overtones, and fundamental tones. This particular construction is economical because it is possible to fabricate the rods 20 from cylindrically shaped stock and by merely turnin same on a lathe. Moreover, no dies or castings are required. Due to their compactness, a minimum amount of material and Weight is required. However, excellent tone quality and uniformity are produced. More specifically referring to the tuned rods 20, it will be noted from Fig. 1 that the circumferentially reduced centrally located portion 21 of each rod extends approximately one-third of the length of the rod, and that the tuning groove 28 is located precisely in the center of the reduced portion 21. It should be borne in mind that to avoid discords and disagreeable distortion in use with an electronically amplified unit, as distinguished from an acoustic type instrument with resonators, it is highly important that each of the tone producing rods 20 have its harmonic tone tuned in Referring more in detail to the drawings,-the double octave relationship to its fundamental or key tone. The proposed construction of the rods with their reduced portions 21 and grooves 28, permits of economical production to roughly tuned state with but slight fin tuning in the following manner:

A uniform cylindrically-shaped rod 20 of appropriate length and diameter having been selected, it is, for rough tuning. grooved or reduced for onethird of the length thereof centrally between its ends, as at 21. As the diameter of this portion 21 becomes less, both the fundamental and the most predominant harmonic tone become lower in pitch. However, the fundamental tone pitch becomes lower more rapidly than the harmonic, so after a certain diameter of the groove 27 is approached, the harmonic and fundamental tone are approximately in the same pitch, except that the lowered harmonic is two octaves higher than the lowered fundamental tone. This operation preferably proceeds no further than a point where the pitch of the fundamental tone is still slightly higher than that of the harmonic. The fine tuning is then readily and easily accomplished by a second groove of a definite width in the exact cen ter of the first groove or reduced portion 21, in the rod, by which to lower the fundamental tone only, without affecting the harmonic tone. This makes it possible to tune the rod in exact double octave relationship by production methods which have heretofore been almost impossible, due to the critical nature of the other types of tuning. If, however, the operator tuning the rod accidentally makes the second groove 28 too deep, thus making the fundamental tone too low in pitch, it is still possible to bring the rod back to double octave pitch. This is done by means of two additional grooves 90 and 9| at opposite ends of reduced portion 21. This lowers the harmonic pitch to the same extent as the fundamental. This makes the whole rod flat with respect to the required note, but in double octave pitch. It is then a simple matter to sharpen the rod by grinding off a small amount of material from the end portions thereof to bring the rod back into exact pitch.

Hammers 29 are arranged along frame means 30 below the rods 2|] respectively. The hammers 29 have felt or other suitable percussion heads 3|. Upright, fabric padded pins 32 on a frame head 33 separate the hammers from each other and maintain their alignment. The hammers 29 are supported by axially alined coil springs 34, whose opposite ends are frictionally maintained in alined openings 35 and 36 in the fram member 30 and in the abutting face of each hammer 29, as best shown in Figure 8. It is believed clear, especially from Figure 4, that the hammers may be staggered from opposite frame members 30.

Actuating means for the hammer comprises push rods 31 which have adjustable tips 38, held in place by set screws 39. The adjustable tips 38 afford contacting means for the hammers 29, as suggested by the broken lines 40 in Figure 2.

'Ihe lower ends of the connecting rods 31 have spring connections 4| with cores 42 of solenoids 43. Cushions 44 are provided to dampen the descent of the cores 42 when the solenoids 43 are tie-energized. When the solenoids 43 are energized, the cores 42 rise therein, causing the hammer 29 to strike its respective rod 20, through the intermediary of the push rod 31. The solenoids 43 are arranged vertically in a support 66, and a cable 91 carries wiring for the solenoids.

Magnetic pick-ups are provided to pick up the vibrations caused by the hammers striking the rods 20. Electro-magnets 45 depend above the rods 20 respectively with set screws 46 adjustably supporting the magnets 45 the desired distances above the rods 20, by means of supporting bars 41. Brackets 48 support the set screws 46. Suitable felt or other non-metallic material 49 may be used between the set screws 46 and the supporting bars 41.

The coils 45 are connected with a suitable vacuum tube amplifier 50, which in turn is connected with a loud speaker 5|, as suggested in Figure 13. The construction of the amplifier 50 and loud speaker 5| are well known to those skilled in the art, so further illustration of same is believed unnecessary.

Means for actuating solenoids 43 is diagrammatically shown in Figure ll. Such means includes keys 52 which respectively connect with the solenoids 43. A sourc of electrical energy is indicated at 53. Normally spaced contacts 54 are closed when the key 52 is moved downwardly about its pivot 55. Engagement of the contacts 54 with each other closes the circuit of the solenoid 43, which causes the core 42 to push the rod 31 upwardly. Any suitable resistors may be used in the circuits respectively, if desired, to minimize arcing and thereby substantially eliminate radio frequency interference.

A mechanical hammer-actuating means is shown in Figure 12. In this form, key 56 is pivotally mounted at 51 and in turn depresses a connecting rod 58. A bell crank 59 connects the rod 58 with push rod 60, which operates to move the hammer 25 to a striking position, similar to the push rod 31. An arm 6| pivotally supports the bell crank 59. A guide 62 directs the lower end of the push rod Bil and a cushion B3 dampens the downward movement of the rod 60.

Damping means are provided for the rods 20. Such means comprise a felt cushion 64, which, in the damping position, engages the end of the rod 20. A head 65 carries the cushion 64. Wires 61 are mounted on levers 68, which are pivoted at 69 on the cross support l8. A plate 10 extends longitudinally of the frame and engages depending arms ll of the levers B8. The felt cushions 12 may be provided on the arms ll facing the plate 70. Fingers 13, supporting the plate 10, are pivoted on the underside of the cross support 18, as suggested at 14.

Flat springs 15 urge the levers 68 and thereby bring the cushions 64 to a damping position.

A laterally extended arm 16, as best shown in Figure 2, is fastened to a connecting rod 11. The upper end of the rod 1! is threaded. Leather washers l8 and 19 are screwed upon the threaded end of the rod ll. The arm 18 and resilient washers 88 are disposed between the leather washers l8 and 19. A solenoid 8| is arranged to actuate its core 82 upward, which, in turn is connected to the rod Tl. Thus when the solenoid 8| in energized, the core 82 rises, thus rotating the lever 68 in a, counter-clockwise direction around the pivot 69, as shown in Figure 2, which removes the damping cushions 64 from the rods 20. When the solenoid 8| is de-energized, the springs l5 move the cushions 64 back to their damping positions, and the core 82 descends to its original position.

If desired, the damping means may be operated mechanically. A pedal 83 is pivoted at 84 and connected by set screw 85 to the rod 71. Thus by depressing the curved end of the pedal 83, rod "IT is raised, thereby removing the damping means from the bars 20.

A damping key 88 is pivoted at 81. Contacts 88 are closed when the key 86 is depressed. The

contacts 88 are in a circuit including the source 53 and the solenoid coil (it. Thus depressing the key 86 closes the circuit of the solenoid coil ill, which releases the damping means.

One of the advantages of my present construction is that the fundamental can be changed. This is done in a very simple manner, to-wit: turning one or more additional circumferential grooves 59 and Bi at one or both sides of the original fundamental groove 28, as shown in Figure 14. The changing fundamental groove or grooves is preferably at the end or ends of the harmonic groove, as shown in Figure 14. When this additional fundamental groove or these additional fundamental grooves are out as stated, the harmonic becomes flat to the same extent as the fundamental. Then by grinding off a relatively small amount from both ends of the rod 20, the entire rod can be brought back into correct pitch.

In the operation of my device it is understood that a series of keys 52, forming a key-board, are operated by the person playing the instru ment. Each of the keys 52 controls the hammer opposite a different one of the rods 20, through the intermediary of the solenoid coils 43 and push rods 37.

Vibrations are set up in the rods 20 by striking same with the hammer heads 3!. These vibrations are electro-magnets 45, since the rods are in the magnetic fields of the magnets d5. These pickedup vibrations are amplified and reproduced through the loud speaker of the instrument. The volume of the vibrations that are picked up by the magnets 45 may be increased by placing the magnets 15 closer to the bars 28. The deeper the fundamental groove, the lower is its tone.

It is believed. clear from the foregoing description, that the damping means may be released electrically by means of the key 85 or mechanically by means of the pedal 83. Moreover, the keys can operate the hammers mechanically, as suggested by the hookup in Figure 12, or electrically by the solenoids 43.

Each rod is tuned with the harmonic tone two octaves above the fundamental tone or frequency. The pitch or tone of a rod in which the harmonic groove has been out, as suggested at 2?, will not vary appreciably upon placing the fundamental groove therein.

One of the advantages is that it may be operated remotely by a key board which controls the solenoids 43. Moreover, due to the fact that the harmonic and fundamental may be placed in the rods 20 by means of a lathe, great accuracy is obtained.

The individual mounting brackets 23 and 25 for the rods 20 make for easy repair and adjustment. Moreover, since only a small weight is sustained by each string or cord 2! and 28, the life of these strings is considerable.

While I have illustrated and described what I now regard as the preferred embodiment of my invention, the construction is, of course, subject to modifications without departing from the spirit and scope of my invention. I, therefore, do not wish to restrict myself to the particular form of construction illustrated and described, but desire to avail myself of all modifications that may fall within the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. An article of manufacture for an instrupieked up electronically by the ment employing musical tones, comprising a cylindrically shaped rod having a circumferential groove forming a reduced portion of substantial length along its central portion to provide 00- tavely spaced fundamental and harmonic tones when the rod is struck, and the said reduced portion itself being circumferentially grooved to provide uniformly pitched fundamental and harmonic tones when the rod is struck.

2. An article of manufacture for an instrument employing musical tones, comprising a cylindrically shaped rod having a circumferential groove forming a reduced portion of substantial length along its central portion to provide octavely spaced fundamental and harmonic tones when the rod is struck, the said reduced portion itself being oircumferentially grooved at its center and at least one end thereof to provide uniformly pitched tones in such relationship.

3. An article of manufacture for an instrument employing musical tones, comprising a rod cylindrically shaped from end to end, having a circumferential groove providing a reduced portion of substantial length between nodal points of the rod, and having a relatively narrow circumferential groove within the base of firstmentioned groove, the overtone and fundamental tone provided by the grooves being substantially tuned to each other in octavely spaced relation.

4. An article of manufacture for an instrument employing musical tones, comprising a cylindrically shaped rod having a circumferential groove forming a reduced portion of substantial length, and the rod being further circumferentially reduced within said groove until the overtone and fundamental tone of the rod are substantially in tune with each other.

5. A. musical member for percussion musical instruments. consisting of a cylindrical rod having intermediate the ends thereof a substantially reduced, elongated cylindrical section, said reduced section being provided with a relatively narrow annular groove therein centrally between the ends thereof, and said reduced section being otherwise of the same diameter substantially throughout its length.

6. A musical member for percussion musical instruments, consisting of a cylindrical rod having intermediate the ends thereof a substantially reduced, elongated and concentric cylindrical section, said reduced section being provided with relatively narrow annular grooves at spaced points in its length, at least one of said grooves being located centrally of the ends of the reduced section, and said reduced section being otherwise of substantially uniform diameter between said grooves and throughout its length upon opposite sides of said central groove.

7. A musical member for percussion musical instruments, consisting of a cylindrical rod provided with a circumferentially reduced portion centrally between end portions of the rod and extending therealorr for approximately onethird of the length of the rod, said reduced portion being of a diameter adapted to roughly lower both fundamental and harmonic tones to a point where the fundamental tone is pitched slightly above two octaves below the harmonic tone, the said reduced portion being provided centrally between the ends thereof with a circumferential tuning groove effective to independently lower the fundamental tone precisely to the same pitch as the harmonic tone.

JOHN O HRUBY, JR, 

